ORA-24247: network access denied by access control list (ACL)

Issue:
ERROR at line 1:
ORA-24247: network access denied by access control list (ACL)
ORA-06512: at "SYS.UTL_TCP", line 17
ORA-06512: at "SYS.UTL_TCP", line 246
ORA-06512: at "SYS.UTL_SMTP", line 115
ORA-06512: at "SYS.UTL_SMTP", line 138
ORA-06512: at "XXX", line 36
ORA-06512: at line 1

Changes:
The problem occured after migrating to 11g from 10g.

Findings:
SQL> select owner,object_name,object_type,status from dba_objects where object_name='MAILSERVER_ACL';
no rows selected

Solution:
Step 1: connect to the Database and create a procedure as given below:
SQL> set serveroutput on
SQL> create or replace procedure mailserver_acl(
aacl varchar2,
acomment varchar2,
aprincipal varchar2,
aisgrant boolean,
aprivilege varchar2,
aserver varchar2,
aport number)
is
begin
begin
DBMS_NETWORK_ACL_ADMIN.DROP_ACL(aacl);
dbms_output.put_line('ACL dropped.....');
exception
when others then
dbms_output.put_line('Error dropping ACL: '||aacl);
dbms_output.put_line(sqlerrm);
end;
begin
DBMS_NETWORK_ACL_ADMIN.CREATE_ACL(aacl,acomment,aprincipal,aisgrant,aprivilege);
dbms_output.put_line('ACL created.....');
exception
when others then
dbms_output.put_line('Error creating ACL: '||aacl);
dbms_output.put_line(sqlerrm);
end;
begin
DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL(aacl,aserver,aport);
dbms_output.put_line('ACL assigned.....');
exception
when others then
dbms_output.put_line('Error assigning ACL: '||aacl);
dbms_output.put_line(sqlerrm);
end;
commit;
dbms_output.put_line('ACL commited.....');
end;
/
Procedure created.

SQL> show errors
No errors.

Step 2: create an ACL as given below:
SQL> begin
mailserver_acl(
'mailserver_acl.xml',
'ACL for used Email Server to connect',
'TEST_USER', -----Username sending mail
TRUE,
'connect',
'abc-smtp-int.MAIL_SERVER.com',  ---Mail Server
25);  ---Port of mail server
end;
/
ACL dropped.....
ACL created.....
ACL assigned.....
ACL commited.....
PL/SQL procedure successfully completed.

Also be sure that mail server entry should be in host file

ACL Views
The DBA_NETWORK_ACLS, DBA_NETWORK_ACL_PRIVILEGES and USER_NETWORK_ACL_PRIVILEGES views display the current ACL settings.

The DBA_NETWORK_ACLS view displays information about network and ACL assignments.
COLUMN host FORMAT A30
COLUMN acl FORMAT A30
SELECT host, lower_port, upper_port, acl FROM dba_network_acls;
HOST LOWER_PORT UPPER_PORT ACL
------------------------------ ---------- ---------- ------------------------------
10.1.10.* /sys/acls/test_acl_file.xml
192.168.2.3 80 80 /sys/acls/test_acl_file.xml
2 rows selected.

The DBA_NETWORK_ACL_PRIVILEGES view displays information about privileges associated with the ACL.
COLUMN acl FORMAT A30
COLUMN principal FORMAT A30
SELECT acl,principal,privilege,is_grant,
TO_CHAR(start_date, 'DD-MON-YYYY') AS start_date,
TO_CHAR(end_date, 'DD-MON-YYYY') AS end_date
FROM dba_network_acl_privileges;
ACL PRINCIPAL PRIVILE IS_GR START_DATE END_DATE
------------------------------ ------------------------------ ------- ----- ----------- -----------
/sys/acls/test_acl_file.xml TEST1 connect true 02-APR-2008
/sys/acls/test_acl_file.xml TEST2 connect false
2 rows selected.

The USER_NETWORK_ACL_PRIVILEGES view displays the current users network ACL settings.
conn test1/test1@db11g
COLUMN host FORMAT A30
SELECT host, lower_port, upper_port, privilege, status
FROM user_network_acl_privileges;
HOST LOWER_PORT UPPER_PORT PRIVILE STATUS
------------------------------ ---------- ---------- ------- -------
10.1.10.* connect GRANTED
192.168.2.3 80 80 connect GRANTED
2 rows selected.

conn test2/test2@db11g
COLUMN host FORMAT A30
SELECT host, lower_port, upper_port, privilege, status
FROM user_network_acl_privileges;
HOST LOWER_PORT UPPER_PORT PRIVILE STATUS
------------------------------ ---------- ---------- ------- -------
10.1.10.* connect DENIED
192.168.2.3 80 80 connect DENIED
2 rows selected.

Checking Privileges
In addition to the ACL views, privileges can be checked using the CHECK_PRIVILEGE and CHECK_PRIVILEGE_ACLID functions of the DBMS_NETWORK_ACL_ADMIN package.

conn sys/password@db11g AS SYSDBA
SELECT DECODE(
DBMS_NETWORK_ACL_ADMIN.check_privilege('test_acl_file.xml', 'TEST1', 'connect'),
1, 'GRANTED', 0, 'DENIED', NULL) privilege
FROM dual;
PRIVILE
-------
GRANTED
1 row selected.

COLUMN acl FORMAT A30
COLUMN host FORMAT A30
SELECT acl,host,
DECODE(DBMS_NETWORK_ACL_ADMIN.check_privilege_aclid(aclid, 'TEST2', 'connect'),
1, 'GRANTED', 0, 'DENIED', NULL) privilege
FROM dba_network_acls;
PRIVILE
-------
DENIED